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When you see how vacuum tubes are made, you immediately understand why the transistor had to be invented: when done correctly, the process is expensive, time-consuming, labor-intensive, and messy. OSHA and the EPA would have big problems with it. I saw how it's done when Dr. Riccardo Kron (footbnote 1) and his wife, Eunice, invited me to the Czech Republic to visit the KR Enterprise facility, in Prague. I'm glad they did—had they just told me about it, I might not have believed them.

Located in a semi-abandoned building that was once part of the…

Analog sources: Simon Yorke, Kuzma Stabi S, turntables; Graham 2.0, Immedia RPM2, Rega RB600 tonearms; Crown Jewel SE, EMT TU, Lyra Parnassus D.C.t, Grado Statement phono cartridges.
Preamplification: Ayre K-1; Audio Research Reference and Musical Fidelity X-LP2 phono sections.
Power amplifiers: Mark Levinson No.335, Ayre V-1.
Loudspeakers: Audio Physic Virgo, Sonus Faber Amati Homage.
Cables: Yamamura Millennium 6000, Cardas Golden Reference, Electra-Glide interconnects; Yamamura Millennium 6000 speaker cables; Yamamura Quantum, Electra-Glide…

The KR Enterprise VT8000 was warmed up for one hour at a third of its rated maximum power. For an amplifier with a tube output stage, it runs relatively cool.

The VT8000's input impedance measured 62.6k ohms. Its measured minimum output impedance is 4.8 ohms at 20Hz; the maximum measured value is 6.6 ohms at 20kHz; and there was some dependence on the exact figure and the load impedance used to make this measurement. This amplifier's frequency response will be very dependent on the loudspeaker with which it is used. Voltage gain into 8 ohms was 26.8dB in…

Description: Hybrid monoblock power amplifier with solid-state input and driver stages, and "vacuum transducer" output stage. Maximum power: 75W RMS (18.75dBW) into 4–8 ohms. Frequency response: 15Hz–35kHz, –3dB; 30Hz–20kHz, –0.5dB. Input sensitivity: switchable 350mV, 1V, 2V, 5V. Input impedance: 100k ohms.
Dimensions: 13.75" W by 10" H by 19.75" D. Weight: 92 lbs.
Serial numbers of units reviewed: 150R, 150L.
Price: $25,000/pair (1999); no longer available (2008). Approximate number of dealers: 5. Warranty: 3 years, parts & labor.
Manufacturer…

Editor: First of all, I would like to take this opportunity to thank Stereophile for permitting Mr. Michael Fremer to review our "top-of-the-line" monoblock amplifier, the VT8000 MK, and to visit our factory in Prague, Czech Republic.

Second, if I may, I would like to respond to a number of inexplicable points that have been raised by your test-bench results that may give erroneous ideas of our sound quality and design philosophy, despite Mr. Fremer's very enthusiastic audition.

My primary duty is to answer, point by point, the results of the curves…

I've been reviewing audio gear for 13 years now, and never, never has the discrepancy between what I heard and what was measured been so great as it was with the KR Enterprise VT8000 MK monoblocks (Stereophile, November 1999). I didn't see the amps' disappointing measurements until the final review was faxed to me for fact-checking. I almost went into toxic shock. I am much more used to having John Atkinson or Tom Norton confirm what I heard; eg, the Audio Physic Virgo review, my first for Stereophile (September 1995…

Editor: I am taking up my pen again to respond...to Mr. Fremer's...additional commentary in his "Analog Corner" feature, where he says, "I was extremely disappointed and surprised to read the discrepancy between the KR's claimed power (75W) and measured power (40W and lower, depending on load impedance and distortion)." From this statement, it is evident from Stereophile's technical testing, [that] we are still in the horse-and-buggy age. Those may have ran very well on plowed fields, but if there is a Ferrari, it certainly cannot give the same performance.…

Among the 10,000, there will doubtlessly be some who have…

Hansen chose to set the input impedance at a high 1M ohm per phase (2M ohms balanced). "You know how, when you load a moving-coil…